Status of the plasma focus source for the laboratory type imaging microscope.

A plasma focus operating in nitrogen is developed as an x-ray source for the laboratory type y-ray microscope. The radiation has to be emitted into the "water window" (2.4 nm - 4.4 nm) with a reciprocal relative bandwidth (RRB) of lambda/Delta-lambda bigger than 200. The nearly coinciding Lyman-alpha line of nitrogen VII lambda = 2.48 nm and the second resonance line of nitrogen VI at lambda = 2.49 nm are chosen. For the use in the microscope the end on diameter of the source has to be about 200 mym with a spatial jitter below 100 mym. A first version of the source including beamline and condenser stage has been tested. Spatial, temporal and spectral properties of the source have been investigated. With a pinhole-grating spectrograph spatial and spectral informations are obtained simultaneously. First experiments with Fresnel condenser zone plates (CZP) as a tool for plasma soft X-ray emission diagnostics are presented. Experimental results show that the gas in the beamline can be used as a filter for undesired radiation. With improved efficency of the zone plates and x-ray detectors the expected plasma emission of about 1 J into the full solid angle from a source with sub 2 a diameter of 200 mym should be sufficent to achieve an exposure with one pulse.